In the production of crude oil from an oil well, it is often necessary to employ artificial lift devices by which the crude oil is lifted up the borehole to the surface of the ground where the crude oil is stored in a tank farm. Usually a pumpjack unit is employed for this purpose and there are some geographical locations where there are more pumpjack units than people. There are those who have spent an entire lifetime studying pumpjack units, and such people are profoundly informed on this subject. The pumpjack units are responsible for a significant amount of the crude oil produced in the USA.
Most pumpjack units include a stuffing box for reciprocatingly receiving a polished rod in sealed relationship therewith. The polished rod is connected to a string of sucker rod that extend downhole to actuate a downhole pump. The seals of the stuffing box become worn with extended usage and must be replaced from time to time and before the produced crude oil is spilled onto the ground. Misalignment between the pumpjack unit and the wellbore causes accelerated wear of the stuffing box seal apparatus. A leaky stuffing box contaminates the surroundings and has often created serious environmental problems when left unattended for long time intervals.
In the past it has been necessary to discontinue production of the well apparatus and to disconnect the polished rod from the horsehead in order to replace the seal apparatus of the stuffing box. Sometime a pack-off is temporarily installed between the polished rod and tubing string to shut in the well and to avoid emitting dangerous gases into the atmosphere. Hence the task of replacing the seals in the stuffing box of a pumpjack unit can become an arduous, time consuming, expensive undertaking.
Self aligning stuffing boxes for pumpjack units have been offered to the industry for many years. The present invention is an improvement over these prior art devices and provides a useful and novel self aligning stuffing box for the polished rod of a pumpjack unit. The improved stuffing box of this invention includes a pack-off in combination therewith by which the borehole annulus is packed off from the stuffing box and thereby enables the stuffing box to be opened and serviced without resorting to the necessity of using a workover rig for killing the well.
Further, the present invention provides a stuffing box having self aligning features in combination with a novel oil reservoir that elongates the expected life of the components of the stuffing box. Moreover, the present invention teaches a self aligning stuffing box having an oil reservoir associated therewith, and means that senses seal failure and provides a signal in response thereto by which the motor controller of the pumpjack unit is de-energized thereby eliminating operation of a hot stuffing box. This unusual and novel feature of the invention eliminates contamination of the well site with crude oil and related products.